A New Pea $20.00 Inside Message Blank Inside Packages of Heartstrings® cards are shrink-wrapped and sold in sets of 10 cards with envelopes. The actual card size is 4 1/4" x 5 1/2". Quantity Add to cart SKU: 23. Categories: Baby - Parenting, Gardening. Related Products Giving is Receiving $20.00 Flower Letter $20.00 How Sweet it Was $20.00 The Plot Thickens $20.00